1. Field of the Invention
The present invention relates to hydraulic work supports for supporting workpieces during machining or other operations. More particularly, the present invention relates to a hydraulic work support having a plunger axially shiftable within a bore of a housing and an improved piston cylinder assembly for shifting the plunger between extended and retracted positions under the influence of hydraulic fluid.
2. Description of the Prior Art
Hydraulic work supports are commonly used to support workpieces during operations thereon. Conventional work supports include a plunger axially shiftable within a bore of a housing. The plunger is shifted upward to an extended position under the influence of fluid pressure to engage the workpiece and is then returned to a lowered, retracted positions under the influence of a compression spring when the workpiece is to be released.
A problem with these types of prior art hydraulic work supports is that the return springs do not provide a controlled rate of return and tend to lose their elasticity and compressive forces after repeated uses. Prior art attempts to provide a hydraulic work support with a plunger that is shifted in both directions under the influence of fluid pressure have been largely unsuccessful due to fluid sealing problems and other problems peculiar to hydraulic work supports.